It has become necessary in certain areas of the United States to switch from gasoline powered vehicles to either propane or natural gas powered vehicles. For instance, some portions of southern California are so heavily plagued by smog that alternative fuels are being strongly pursued to reduce the air pollution.
U.S. Pat. No. 5,323,812 to Wilcox issued Jun. 28, 1994 is directed toward a pressure locked coupling for use with propane and natural gas. The coupling of the '812 patent securely couples the source of the gas to the vehicle. The present invention adds filters to the coupler and the nipple. The filters can be in both the coupler and the nipple, the coupler only or the nipple only.